Nanode - a cheap networked arduino clone

The arduino, the open source microcontroller board, has had MQTT support for a
long time in the form of Nick O'Leary's arduino client. It does however
require networking support which has traditionally provided by an add on
shield, which increases the cost of the system.

The Nanode is an arduino compatible board which includes network support and
can be built for approximately the same cost as a normal arduino board. It's
still a work in progress, but is definitely worth a look if you want to use low
power MQTT capable sensors/controllers.